Plastic preform for a container

Abstract

Plastic preforms for containers. This invention relates to preforms (1) for containers manufactured by stretch blow molding, which are made of plastic and include at least: a body (2) symmetrical about a vertical central axis (X), the body (2) having an outer wall (2a) and an inner wall (2b), the radial distance between the outer wall (2a) and the inner wall (2b) defining the wall thickness; an open neck (3) extending from the upper end of the body (2), the neck (3) being separated from the body (2) by an annular flange (4); and a bottom (5) closing the body (2) from the lower end (6), the bottom (5) being symmetrical about the central axis (X), characterized in that the body (2) is generally cylindrical. Towards the bottom (5), the wall thickness gradually increases from the flange (4) along the varying height Hv. The wall thickness of the main body (2) below the flange is equal to E2. The height Hv is strictly less than the height H between the flange (4) and the lower end (6) of the main body (2) and strictly greater than 0.35H. The varying height Hv is the average of the varying height Hv1 of the outer wall (2a) and the varying height Hv2 of the inner wall (2b), so that the wall thickness E2 gradually increases along the height Hv. The wall thickness of the main body (2) between the height Hv and the lower end (6) of the main body is approximately constant and equal to E1. E1 corresponds to the wall thickness of the main body (2) from the maximum varying height Hv1 or Hv2.

Description

Technical Field

[0001] This invention relates to the manufacture of containers from plastic preforms, particularly polyethylene terephthalate (PET) and / or recycled polyethylene terephthalate (rPET). More specifically, this invention relates to a preform for shaping containers in a mold having a container cavity by blow molding or stretch blow molding, or in a free-form manner (i.e., without a mold). Background Technology

[0002] Well-known containers typically include: generally rotationally symmetrical sidewalls extending about a central axis; a neck extending in an extension of the sidewalls through which the container is used for filling and emptying; and a bottom extending laterally from the lower end of the body through which the container is used to rest against a flat surface.

[0003] In addition, preforms typically include: a generally cylindrical body (for forming the sidewalls of the container); an open neck extending from the upper end of the body into an extension of the body, the neck being separated from the body by a flange (the neck remains unchanged during the container forming process); and a bottom of the body that closes at the lower end of the body (for forming the bottom of the container).

[0004] To form a container from a preform, the body and bottom of the preform are first heated to a temperature above the material's glass transition temperature (approximately 72 to 75°C for PET). Then, pressurized fluid (usually air) is injected into the preform, subjecting the body to simultaneous axial and radial expansion until it reaches the desired shape for the container body. Axial expansion is typically facilitated by stretching using so-called stretch bars.

[0005] Heating typically takes place in a heating unit (also called a furnace) equipped with multiple infrared radiation sources to which the preform is exposed. These sources are usually halogen lamps, whose radiation includes a broad spectrum of near-infrared (and possibly some mid-infrared) light, as well as at least a portion of the visible spectrum. The main disadvantages of halogen lamps are their poor directionality (or even omnidirectionality) and relatively short lifespan.

[0006] To overcome these drawbacks, the applicant has developed an alternative heating technology based on the use of monochromatic (or quasi-monochromatic) radiation sources, which offer better directionality and longer lifespan. See, for example, European patent application EP 2720 842 (Sidel Participations), which describes a method for heating a preform using a matrix of vertical cavity surface-emitting lasers (VCSELs).

[0007] Extensive testing of this new technology, known as a laser furnace, on preforms of all shapes and sizes has shown that heating of preforms can be further improved by developing preform shapes that differ from those known and used in halogen furnace technology. Therefore, it appears necessary to redesign the profile and dimensions of the preforms.

[0008] In response, the applicant has proposed a preform that, when exposed to monochromatic or quasi-monochromatic infrared radiation, can be heated relatively uniformly, i.e., without the formation of undesirable localized overheating areas. This preform suitable for laser furnaces is specifically described in the applicant's filing WO2017 / 103372A1.

[0009] Document WO2017 / 103372A1 describes a plastic container preform comprising: a body symmetrical about a central axis; an open neck extending in an extension of the body, the neck being separated from the body by a radially projecting flange; and a bottom of the body closed on the opposite side of the neck; wherein the body has a recessed portion in an axial section and wherein: B ≤ 0.9A and 0.5C < C' < 0.95C, where A is the total diameter of the body, measured below the flange; B is the outer diameter of the bottom, measured at its connection with the body; C is the total height of the body and the bottom, measured from the flange; C' is the axially measured height of the recessed portion of the body, and the recessed portion has an outer radius of curvature RE on the outer wall in an axial section, satisfying 1.5C ≤ RE ≤ 10C.

[0010] These characteristics help minimize refraction in the material, which is beneficial for better heating quality.

[0011] However, these preforms are not optimized for all packaging sizes and neck types to achieve an ideal fit, especially with significant weight reduction, while also adhering to the injection molding rules and constraints of preforms. Therefore, these preforms cannot provide a satisfactory material distribution for all container sizes, and ultimately cannot achieve weight reduction in containers manufactured from these preforms while ensuring good container quality. Summary of the Invention

[0012] Therefore, one of the objectives of this invention is to overcome all or part of the above-mentioned disadvantages by providing a preform that is simple in design and low in cost. This preform is particularly suitable for heating in a laser furnace to provide better material distribution for all container sizes, thereby achieving weight reduction of containers manufactured from such preforms while ensuring good container quality.

[0013] Therefore, according to the present invention, a preform for manufacturing containers by stretch blow molding is provided. The preform is a plastic preform and includes at least: a body that is rotationally symmetrical about a vertical central axis, the body having an outer wall and an inner wall, the radial distance between the outer wall and the inner wall defining the wall thickness; an open neck extending from the upper end of the body in an extension of the body, the neck being separated from the body by an annular flange; and a bottom that closes the body from the lower end of the body, the bottom being rotationally symmetrical about a central axis, characterized in that the body is generally cylindrical in shape. Along the bottom direction at the so-called varying height Hv, the wall thickness gradually increases from the flange, and the main body wall thickness below the flange is equal to E2. The varying height Hv is strictly less than the height H between the flange and the lower end of the main body and strictly greater than 0.35H. The varying height Hv is the average of the varying height Hv1 of the outer wall and the varying height Hv2 of the inner wall, such that the wall thickness E2 gradually increases along the varying height Hv, and the main body wall thickness between the varying height Hv and the lower end of the main body is approximately constant and equal to E1, where E1 corresponds to the main body wall thickness from the largest of the heights Hv1 and Hv2.

[0014] Preferably, the change in the thickness V of the main body wall at the varying height Hv is equal to E1-E2, and the change V is between 0.25E1 ​​and 0.75E1.

[0015] Furthermore, advantageously, the rate of change T of the main body wall thickness is equal to the change height Hv divided by the change amount V (T=Hv / V), and the rate of change T is between 10 and 40.

[0016] Preferably, the rate of change T of the main body wall thickness is between 20 and 25.

[0017] Furthermore, at varying heights Hv, the average outer diameter D1 of the main body gradually increases from the flange toward the lower end of the main body.

[0018] Furthermore, at varying heights Hv, the average inner diameter D2 of the main body remains constant from the flange toward the lower end of the main body.

[0019] According to one embodiment of the preform of the invention, the average outer diameter D1 of the body is constant from the flange toward the lower end of the body over a varying height Hv.

[0020] Furthermore, at varying heights Hv, the average inner diameter D2 of the main body gradually decreases from the flange toward the lower end of the main body.

[0021] According to another embodiment of the preform according to the invention, over a varying height Hv, the average outer diameter D1 of the body gradually decreases from the flange toward the lower end of the body, and the average outer diameter D2 of the body gradually decreases from the flange toward the lower end of the body, with the average outer diameter D2 decreasing faster than the average inner diameter D1.

[0022] Incidentally, the bottom of the preform is roughly hemispherical.

[0023] Furthermore, the wall thickness at the bottom is preferably less than or equal to the main body wall thickness E1 of the preform.

[0024] Another object of the present invention relates to a method for manufacturing a container by blow molding or stretch blow molding, comprising at least the following steps: providing a preform according to the invention; heating the body of the preform by exposing the body of the preform to monochromatic or quasi-monochromatic infrared radiation of a predetermined intensity; and molding the container by injecting pressurized fluid into the preheated preform.

[0025] In addition, the method includes a step of introducing the preform into a mold having a container cavity between the heating step and the molding step.

[0026] The final object of the present invention relates to a mold for molding a preform according to the present invention, comprising a mold body, a mold base and a core, wherein the sidewalls of the mold body have molding surfaces that match the outer surface of the body of the preform, the mold base has molding surfaces that match the outer surface of the bottom of the preform, and the core has molding surfaces that match the inner surface of the preform. Attached Figure Description

[0027] Other advantages and features will become clearer from the following description, with reference to the accompanying drawings, of several embodiments of the preform according to the invention given by way of non-limiting example, in which:

[0028] Figure 1 This is a front cross-sectional view of a preform for manufacturing containers according to the present invention;

[0029] Figure 2 This is a front cross-sectional view of a variation of the preform for manufacturing containers according to the present invention;

[0030] Figure 3 This is a schematic diagram illustrating the manufacture of a container from a preform according to the present invention;

[0031] Figure 4 It is a cross-sectional view of a mold that allows for the molding of preforms according to the present invention. Detailed Implementation

[0032] In the following description, the same numerical designations represent the same elements. Furthermore, the individual views are not necessarily drawn to scale.

[0033] Figure 1 The image shows a plastic preform 1, made of plastic such as PET (polyethylene terephthalate) and / or rPET (recycled polyethylene terephthalate), for containers to be formed from such preforms by blow molding or stretch blow molding.

[0034] Each preform 1 first includes a body 2 that extends in a manner symmetrical about a central axis X. According to an advantageous approach suitable for most applications, the body 2 is generally cylindrical. The body 2 of the preform 1 serves to form the body and shoulder of a container (not shown in the figures).

[0035] Each preform 1 further includes an open neck 3 that extends from the upper end of the body into an extension of the body 2. The neck 3 has its final shape and is used to maintain its shape throughout the container's molding and lifespan.

[0036] The neck 3 is advantageously separated from the body 2 by a radially projecting flange 4 through which the preform 1 (subsequent container) is suspended (or more generally supported) during various operations such as preform 1 conveying, heating or container forming, and then filling, capping and labeling of the container.

[0037] Each preform 1 further includes a bottom 5 that closes the body 2 from the lower end 6 of the main body, i.e., the material of the bottom 5 extends from the lower end 6 of the (generally cylindrical) body 2 to radially engage the central axis X and thus close the preform 1 on the opposite side of the neck 3. The bottom 5 is rotationally symmetrical about the central axis X, i.e., it remains unchanged in any longitudinal section (in other words, a section through the central axis X).

[0038] Therefore, the plastic preform 1 for manufacturing containers by stretch blow molding according to the present invention comprises at least: a body 2 that is symmetrical about a vertical central axis X, the body 2 having an outer wall 2a and an inner wall 2b, the radial distance between the outer wall 2a and the inner wall 2b defining the wall thickness; an open neck 3 extending from the upper end of the body in an extension of the body 2, the neck 3 being separated from the body by an annular flange 4; and a bottom 5 that closes the body 2 from the lower end 6 of the body, the bottom 5 being symmetrical about the central axis X.

[0039] The main body 2 is generally cylindrical in shape. At a so-called varying height Hv towards the bottom 5, its wall thickness gradually increases from the flange 4. The wall thickness below the flange is equal to E2. The varying height Hv is strictly less than the height H between the flange 4 and the lower end 6 of the main body and strictly greater than 0.35H. The varying height Hv is the average of the varying height Hv1 of the outer wall 2a and the varying height Hv2 of the inner wall 2b, such that the wall thickness E2 gradually increases at the varying height Hv. The wall thickness of the main body 2 between the varying height Hv and the lower end of the main body 2 is approximately constant and equal to E1, where E1 corresponds to the wall thickness of the main body 2 at the maximum height Hv1 or Hv2.

[0040] Furthermore, preferably, the height variation Hv1 of the outer wall 2a of the main body 2 and the height variation Hv2 of the inner wall 2b of the main body 2 are between 0.7Hv and 1.3Hv.

[0041] Furthermore, the change in wall thickness V of the main body 2 at the varying height Hv is equal to E1-E2, and the change in V is preferably between 0.25E1 ​​and 0.75E1.

[0042] Furthermore, advantageously, the rate of change T of the wall thickness of the main body 2 is equal to the change height Hv divided by the change amount V (T=Hv / V), and the rate of change T is between 10 and 40, preferably between 20 and 25.

[0043] Furthermore, along the varying height Hv, the average outer diameter D1 of the main body 2 gradually increases from the flange 4 toward the lower end 6 of the main body 2.

[0044] Furthermore, at varying heights Hv, the average outer diameter D2 of the main body 2 remains constant from the flange 4 toward the lower end 6 of the main body 2.

[0045] Incidentally, the bottom 5 of the preform 1 is generally hemispherical, and the wall thickness of the bottom is preferably less than or equal to the wall thickness E1 of the body 2 of the preform 1.

[0046] Of course, the bottom 5 of the preform 1 can have any shape and any wall thickness, which does not depart from the scope of the invention.

[0047] According to one implementation variant, refer to Figure 2 The preform 1 includes a body 2 extending in a manner symmetrical about a central axis X, in the same manner as before. According to an advantageous approach suitable for most applications, the body 2 is generally cylindrical. The body 2 of the preform 1 serves to form the body and shoulder of the container.

[0048] Each preform 1 also includes an open neck 3 that extends from the upper end of the body into an extension of the body 2.

[0049] The neck 3 is advantageously separated from the body 2 by a radially projecting flange 4 through which the preform 1 (subsequent container) is suspended (or more generally supported) during various operations such as conveying, heating or forming the preform 1, and filling, capping and labeling the container respectively.

[0050] Each preform 1 also includes a bottom 5 that closes the body 2 from the lower end 6 of the body, i.e., the material of the bottom 5 extends from the lower end 6 of the (generally cylindrical) body 2 to radially engage the central axis X and thus close the preform 1 on the opposite side of the neck 3. The bottom 5 is rotationally symmetrical about the central axis X, i.e., it remains unchanged in any longitudinal section (in other words, a section through the central axis X).

[0051] Therefore, the plastic preform 1 for manufacturing containers by stretch blow molding according to the present invention comprises at least: a body 2 that is symmetrical about a vertical central axis X, the body 2 having an outer wall 2a and an inner wall 2b, the radial distance between the outer wall 2a and the inner wall 2b defining the wall thickness; an open neck 3 extending from the upper end of the body in an extension of the body 2, the neck 3 being separated from the body 2 by an annular flange 4; and a bottom 5 that closes the body 2 from the lower end 6 of the body, the bottom 5 being symmetrical about the central axis X.

[0052] The main body 2 is generally cylindrical in shape, and its wall thickness gradually increases from the flange 4 along the so-called variable height Hv towards the bottom 5. The wall thickness of the main body below the flange 4 is equal to E2. The variable height Hv is strictly less than the height H between the flange 4 and the lower end 6 of the main body 2 and strictly greater than 0.35H. The variable height Hv is the average of the variable height Hv1 of the outer wall 2a and the variable height Hv2 of the inner wall 2b, such that the wall thickness E2 gradually increases along the variable height Hv, and the wall thickness of the main body 2 between the variable height Hv and the lower end of the main body is approximately constant and equal to E1, where the thickness E1 corresponds to the wall thickness of the main body 2 at the maximum height Hv1 or Hv2.

[0053] Furthermore, preferably, the height variation Hv1 of the outer wall 2a of the main body 2 and the height variation Hv2 of the inner wall 2b of the main body 2 are between 0.7Hv and 1.3Hv.

[0054] Furthermore, the change in wall thickness V of the main body 2 at the varying height Hv is equal to E1-E2, and the change in V is preferably between 0.25E1 ​​and 0.75E1.

[0055] Furthermore, advantageously, the rate of change T of the main body wall thickness is equal to the change height Hv divided by the change amount V (T=Hv / V), and the rate of change T is between 10 and 40, preferably between 20 and 25.

[0056] The difference between this preform implementation variation and the above-mentioned implementation variation is that, over the varying height Hv, the average outer diameter D1 of the main body 2 is constant from the flange 4 toward the lower end 6 of the main body 2.

[0057] Furthermore, along the varying height Hv, the average outer diameter D2 of the main body 2 gradually decreases from the flange 4 toward the lower end 6 of the main body 2.

[0058] In the same manner as described above, the bottom 5 of the preform is also generally hemispherical in shape, and the wall thickness of the bottom 5 is preferably less than or equal to the wall thickness E1 of the main body of the preform.

[0059] Of course, the bottom 5 of the preform 1 can have any shape and any wall thickness, which does not depart from the scope of the invention.

[0060] also, Figure 3 The image shows, very schematically, an apparatus 10 for manufacturing containers from the preform 1 as described above.

[0061] The device 10 includes a heating unit 11, which is equipped with multiple radiation sources 12 that emit monochromatic or quasi-monochromatic electromagnetic radiation in the infrared band.

[0062] In theory, a monochromatic radiation source is an ideal radiation source that emits a single-frequency sine wave. In other words, its frequency spectrum consists of a single spectral line (Dirac function) with a spectral width of zero.

[0063] In reality, such a radiation source does not exist. The actual radiation source is at most quasi-monochromatic, that is, its frequency spectrum extends on a narrow but non-zero band, and the center of this band is at the dominant frequency with the greatest radiation intensity.

[0064] The radiation sources 12 are preferably arranged in a matrix; for example, they are VCSEL type laser diodes, each of which emits radiation with a power of tens of milliwatts and a wavelength of about 1 μm.

[0065] The apparatus 10 also includes a molding unit 13, which includes at least one mold 14 having a container cavity. In practice, the molding unit 13 may include a series of molds 14 mounted on a rotating turntable. The molding unit 13 includes an injection device 15 for each mold 14, the injection device including a nozzle 16 capable of sealingly abutting the upper surface of the mold 14 and connected to a pressurized fluid (e.g., air) source 17 via a distributor 18 (e.g., a solenoid valve). The apparatus also includes a control unit 19 connected to the fluid source 17 and the distributor 18 to control their pressure regulation, opening, and closing accordingly.

[0066] In the example shown, the molding unit 13 also includes a tension bar 20 for each mold 14, which is slidably mounted relative to the mold 14 to ensure stretching of the preform 1 during blow molding.

[0067] Therefore, the following steps are taken to form the container.

[0068] First, for example, the preform 1 as described above is provided from a storage container that stores all identical preforms 1.

[0069] Then, the body 2 and bottom 5 of the preform 1 are heated in the heating unit 11 by being exposed to monochromatic or quasi-monochromatic infrared radiation of a predetermined intensity emitted by the radiation source 12. During heating, the preform 1 is rotated about its axis X to ensure that its body 2 and bottom 5 are exposed to radiation uniformly or non-uniformly.

[0070] Considering the preform shape and size design as described above, it was observed that preform 1 refracts less radiation received. This results in better energy distribution in the material, better heating control, and a better match between the power distribution regulated at radiation source 12 and the heat distribution observed on preform 1 (e.g., by a thermal imager).

[0071] The heated preform 1 is then introduced into the mold 14, and the container is formed by injecting pressurized fluid (e.g., air) into the preform 1 from the fluid source 17.

[0072] Injection molding may include the use of a tension bar (see...) Figure 3 The step of axially stretching the preform 1 using the tension rod 20 in the middle.

[0073] As a variation, molding can be performed freely, i.e. without the need for mold 14.

[0074] also, Figure 4 The middle part shows the mold 30 used to form the preform 1 as described above.

[0075] More specifically, the mold 30 shown is advantageously designed to allow manufacturing by simple injection of plastic materials (typically PET and / or rPET). Figure 1 The preform 1 is shown. This mold 30 includes, on the one hand, a mold body 31 having a sidewall 32 having a molding surface that matches the outer surface of the preform 1 at the body 3; it also includes a mold bottom 33 having a molding surface that matches the outer surface of the preform 1 at the bottom 7; on the other hand, the mold includes a core 34 having a molding surface that matches the inner surface of the preform 1.

[0076] The mold body 31 and the mold base 33 are fixed, while the core 34 is movable relative to them to allow the preform 1 to be removed and demolded once it is formed.

[0077] like Figure 4 As shown, the sidewalls 32 and the mold base 33 have grooves 35 around their periphery. These grooves, together with the outer shell (not shown), form a flow channel for cooling fluid (e.g., water) to ensure that the preform 1 is cooled through its outer wall immediately after molding.

[0078] Similarly, Figure 4As shown, the core 34 is provided with a hollow outer shell 36 having a molding surface that matches the inner surface of the preform 1, and a central injector 37, which is also hollow and has a notch 38 at its lower end. Cooling fluid (e.g., water) is introduced into the injector 37, passes through the notch 38, and circulates between the injector 37 and the outer shell 36 to regulate the temperature of the outer shell to a suitable value, thus ensuring that the preform 1 is cooled through its inner surface immediately after molding.

[0079] Material (e.g., PET and / or rPET) is injected in molten form through an injection device (not shown) through an opening 39 in the center of the mold base 33.

[0080] It can be observed that, as a variation, it is conceivable to mold the preform 1 using techniques other than simple injection, particularly injection-compression.

[0081] Finally, it is clear that the examples given are merely illustrative and are by no means limiting to the application areas of this invention.

Claims

1. A preform (1) for manufacturing containers by stretch blow molding, the preform being a plastic preform, the preform comprising at least: The main body (2) is symmetrical about a vertical central axis (X). The main body (2) has an outer wall (2a) and an inner wall (2b). The radial distance between the outer wall (2a) and the inner wall (2b) defines the wall thickness of the main body. The open neck (3) extends from the upper end of the main body in the extension of the main body (2). The neck (3) is separated from the main body (2) by an annular flange (4). And the bottom (5), the bottom closes the main body (2) from the lower end (6) of the main body, the bottom (5) is symmetrical about the central axis (X), characterized in that the main body (2) is in a generally cylindrical shape, and its wall thickness gradually increases from the flange (4) in the direction of the bottom (5) at the so-called variable height Hv, the wall thickness of the main body (2) below the flange is equal to E2, wherein the variable height Hv is strictly less than the height H between the flange (4) and the lower end (6) of the main body (2) and strictly greater than 0.35H, the variable height Hv is the average of the variable height Hv1 of the outer wall (2a) and the variable height Hv2 of the inner wall (2b), such that the wall thickness E2 of the main body below the flange gradually increases at the variable height Hv, and the wall thickness of the main body (2) between the variable height Hv and the lower end (6) of the main body is approximately constant and equal to E1, wherein E1 corresponds to the wall thickness of the main body (2) from the largest height of heights Hv1 and Hv2.

2. The preform (1) according to claim 1, characterized in that, The height variation Hv1 of the outer wall (2a) and the height variation Hv2 of the inner wall (2b) are between 0.7Hv and 1.3Hv.

3. The preform (1) according to claim 1 or 2, characterized in that, The change in wall thickness (2) of the main body at the varying height Hv is equal to E1-E2, and the change in thickness V is between 0.25E1 ​​and 0.75E1.

4. The preform (1) according to claims 1 and 3, characterized in that, The rate of change of the wall thickness of the main body (2) is equal to the change height Hv divided by the change amount V, that is, T=Hv / V, and the rate of change T is between 10 and 40.

5. The preform (1) according to claim 4, characterized in that, The rate of change T of the wall thickness of the main body (2) is between 20 and 25.

6. The preform (1) according to any one of claims 1 to 5, characterized in that, At varying heights Hv, the average outer diameter D1 of the main body gradually increases from the flange (4) toward the lower end (6) of the main body (2).

7. The preform (1) according to any one of claims 1 to 6, characterized in that, At varying height Hv, the average outer diameter D2 of the main body (2) is constant from the flange (4) toward the lower end (6) of the main body (2).

8. The preform (1) according to any one of claims 1 to 5, characterized in that, At varying height Hv, the average outer diameter D1 of the main body (2) is constant from the flange (4) toward the lower end (6) of the main body (2).

9. The preform (1) according to any one of claims 1 to 6, characterized in that, At varying heights Hv, the average outer diameter D2 of the main body (2) gradually decreases from the flange (4) toward the lower end (6) of the main body (2).

10. The preform (1) according to any one of claims 1 to 5, characterized in that, At varying heights Hv, the average outer diameter D1 of the main body (2) gradually decreases from the flange (4) toward the lower end (6) of the main body (2), and the average outer diameter D2 of the main body (2) gradually decreases from the flange (4) toward the lower end (6) of the main body (2), with the average outer diameter D2 decreasing faster than the average inner diameter D1.

11. The preform (1) according to any one of claims 1 to 10, characterized in that, The wall thickness E1 of the main body (2) varies by ±20% between the height Hv and the lower end (6) of the main body (2).

12. The preform (1) according to any one of claims 1 to 11, characterized in that, The bottom (5) is roughly hemispherical.

13. The preform (1) according to any one of claims 1 to 12, characterized in that, The bottom (5) has a wall thickness less than or equal to the wall thickness E1 of the main body (2) of the preform (1).

14. A method for manufacturing a container by blow molding or stretch blow molding, the method comprising at least the following steps: - Provide a preform (1) according to any one of claims 1 to 13; - The body (2) of the preform (1) is heated by exposing the body of the preform to monochromatic or quasi-monochromatic infrared radiation of a predetermined intensity; and - The container is formed by injecting pressurized fluid into a preheated preform (1).

15. The method according to claim 14, characterized in that, The method further includes, between the heating body step and the forming container step, a step of introducing the preform (1) into a mold (14) having a container cavity.

16. A mold (14) for forming a preform (1) according to any one of claims 1 to 13, the mold comprising at least a mold body (31), a mold base (33) and a core (34), the sidewall of the mold body having a forming surface matching the outer surface of the body (2) of the preform (1), the mold base having a forming surface matching the outer surface of the bottom (5) of the preform (1), and the core having a forming surface matching the inner surface of the preform (1).

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